1. The Technical Field
The present invention is directed to an electronic control system for a door latch release mechanism, including means for rejecting false actuation signals caused by environmental effects or otherwise.
2. The Related Art
Common automobile door latches are purely mechanical devices having a mechanical latch and a mechanical release mechanism operated by a mechanical pushbutton, pull handle, or the like. In recent years, some automobile manufacturers have offered electrically-operated door latch mechanisms. These mechanisms typically use a conventional mechanical latch with an electrically-operated release mechanism controlled by a conventional membrane switch. Membrane switches typically are sealed to environment, and, therefore, they are a logical design choice for use on an automobile's exterior. However, under its protective cover, a membrane switch is basically a mechanical push button switch whose movable contact is moved by flexing the protective cover. As such, the protective cover can deteriorate and crack, allowing moisture and contaminants to enter the internals of the switch, ultimately leading to failure of the switch. Further, ice buildup, as is common in northern climates in the winter months, can render a membrane switch inoperable.
Field effect sensors which respond to proximity or touch of a stimulus, for example, touch of human finger, are superior to membrane switches in that they are solid state devices having no moving parts to wear out. However, conventional field effect sensors are not ideally suited for harsh environments, such as the outside of an automobile, because they also can be unintentionally actuated by other stimuli, such as pooled or flowing water or other contaminants. As such, an electrically operated automobile door latch controlled by a conventional field effect sensor could release spuriously and unintentionally when the automobile is parked in the rain or run through a carwash.